As you note, the hardware seems underpowered. Especially for Volumio, which has always been on the heavy side.
I’ve used a bunch of other streamers, including several Pi-based ones with Ropieee, which were basically flawless. I got the Stream in a hurry for a new system during the time Pis were very hard to find, and it never worked as reliably as those Pi+Pi2AES assemblies. However, for this particular DAC (Soekris dac2541), what I prefer is USB, so the Pi2Design hardware is not relevant, nor something like the Holo Red. On two other systems, I use teeny mini PCs running the NAA image with Intona USB isolators to drive Holo DACs, totally flawless for several years.
My take - not the strongest wi-fi on this thing (a problem for DSD and 24/192), so I have it plugged into the Ethernet port on a Mesh Wi-fi extender thingumabob. Basically though mine has worked and continues to work flawlessly as the daily driver in my office system right up to 24/192 and single-rate DSD over USB to a number of different DACs (right now my Quad Vena II integrated amp).
I have never updated the firmware, as I’m a firm believer in not updating f/w on devices that are working. I also tend not to power it down/shut it down these days as it is in use every day.